There is a frequent need to be able to reduce the temperature of a particular site on an animal or person, a reaction mixture, device, or the like. There are many instances where the normal coolants, such as ice, refrigerated cold packs, or the like, are not readily available or convenient. This may be particularly true where the cooling may be too severe, refrigeration may not be available, or storage of the coolant may be inconvenient. Recognizing this problem, cold pack devices have been developed which employ endothermic solubilization or reactions to provide cooling. By providing a portion of the reactants in one cell of the pack and the other portion in another cell, where the barrier cah be broken at will, cooling can be provided without the various problems associated with refrigeration.
While these devices find wide use, they suffer from many deficiencies. One of the problems of concern is te relatively short lifetime of the pack, so as to require a relatively large number of packs to maintain the cooling for an extended period of time. There is, therefore, a substantial interest in being able to improve such cold packs and greatly extend their useful lifetime.